Just purchased a 1997 Monaco Dynasty with Aqua hot heat. Previous owner told me the fluid used in the system is a 50 50 mix of antifreeze and diesel fuel. I have been reading some of the threads on this site and am now wondering if this is the proper mix. Also from what he said the system has to be topped up quite often but I don't see any evidence of leakage HELP

Sounds like you've got a really HOT situation on your hands.

Roger Berke is the only one you should listen to and ask questions about your Aqua-Hot system.

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The proper procedure to remove as much existing coolant and replace it with new is as follows:

Make sure that electric element does not get accidentally turned on with no coolant in the boiler tank. Turn off circuit breaker in your AC panel. If element gets turned on with no liquid in tank, it will immediately fail.

Drain existing coolant through drain (in your model the drain goes through the floor of the coach). You will get around 16 gallons of coolant.

Fill boiler tank with tap water. Turn on diesel burner and bring unit to operating temperature. Turn on interior heat so that you also flush out the coolant lines to interior heat exchangers.

Shut unit down and drain.

Fill unit with coolant (50% coolant and 50% distilled water).

Depending on how much diesel fuel was added, you may want to flush twice before adding proper coolant.

Before you do anything, re-read Crabby Mike's response. See if the coolant smells like diesel fuel.

No one in their right mind would put diesel fuel in with the coolant.

If the previous owner put Diesel in the coolant, your probably going to find a lot more problems than what you have with the Aqua-Hot.

I'm with you there! And I didn't mean to suggest whether the original owner did or didn't actually use diesel fuel in his coolant, just that there was a colossal misunderstanding somewhere along the line. I too would give the coolant a sniff test before changing out -- seems like 50% diesel would be pretty easy to detect.

But above all -- when it comes to Aqua-Hot systems, do whatever Roger tells you to!

I'm with you there! And I didn't mean to suggest whether the original owner did or didn't actually use diesel fuel in his coolant, just that there was a colossal misunderstanding somewhere along the line. I too would give the coolant a sniff test before changing out -- seems like 50% diesel would be pretty easy to detect.

But above all -- when it comes to Aqua-Hot systems, do whatever Roger tells you to!

SORRY FOR THE WAIT, IT'S BEEN A BUSY SUMMER AND HERE'S WHAT HAPPENED,,I phoned the previous owner and asked him where he got the info from. He told me the RV dealership where he purchased the coach had a few gallons premixed and them stored in one of the slide out bins. I found the containers he referred to which were marked in felt pen diesel/antifreze for whatever reason, after sniffing each container have conclusively determined I can not smell any diesel, thank god!!